340 2 barrel manifold

Ok, funny story here. Long ago, an acquaintance had a '71 Duster. 3 speed in the floor, 318 w 8 3/4 rear. Never thought anything of it - lots of 318 3/floor cars got 8 3/4. He sold the car to another friend, we pull the motor for a rebuild and find a 340 inder the 2 bbl intake. This was long before checking numbers to the block, and the car got parted, so never knew if it was "original".